EXHIBIT 32.1
CERTIFICATION OF
CHIEF EXECUTIVE OFFICER
OF PIONEER NATURAL RESOURCES COMPANY
PURSUANT TO 18 U.S.C. § 1350
I, Scott D. Sheffield, Chairman and Chief Executive Officer of Pioneer Natural Resources Company (the “Company”), hereby certify that the accompanying report on Form 10-K for the year ended December 31, 2004, as amended, and filed with the Securities and Exchange Commission on the date hereof pursuant to Section 13(a) of the Securities Exchange Act of 1934 (the “Report”) by the Company fully complies with the requirements of that section.
I further certify that the information contained in the Report fairly presents, in all material aspects, the financial condition and results of operations of the Company.
| /s/ Scott D. Sheffield | ||||||
| Name: | Scott D. Sheffield, Chairman and | |||||
| Chief Executive Officer | ||||||
| Date: | March 10, 2005 |
